Black students at a Malden charter school who wear their hair in braids are facing detention and suspension by administrators who say the hairstyles violate the school’s dress code. Parents describe the crackdown as racist.

Colleen Cook, whose twin 15-year-old daughters, Deanna and Mya, attend the Mystic Valley Regional Charter School, said Thursday evening that her children have served multiple detentions since last week and could be suspended.

“They teach them at a very high academic level and I appreciate that, and that’s why they go to the school,” Cook said. “But, unfortunately, they don’t have any sensitivity to diversity at all.”

Two other mothers said their black or biracial children had been subjected to discipline or questioning over their hairstyles — braids with extensions — which the parents describe as important expressions of culture.

The school issued a statement defending its actions, saying that Mystic Valley Charter serves a diverse population and that many students go on to attend top colleges and universities.

“One important reason for our students’ success is that we purposefully promote equity by focusing on what unites our students and reducing visible gaps between those of different means,” the statement said.

“Our policies, including those governing student appearance and attire, foster a culture that emphasizes education rather than style, fashion, or materialism,” the statement said. “Our policy on hair extensions, which tend to be very expensive, is consistent with, and a part of, the educational environment that we believe is so important to our students’ success.”

School officials were not available for interviews Thursday evening, a spokesman said.

Cook said the school’s policy against braids that include hair extensions — additional hair that is woven in — disproportionately affects black children. Cook and her husband adopted five black children — all siblings — and four have attended Mystic Valley since kindergarten, she said.